The invention relates to electric consumers in motor vehicles having current flow detection devices and a control device for current flow interruption.
In principle, safety devices in series with electric consumers have been known for a long time. Mention need only be made of melting safety devices, bimetallic switches, automatic safety devices, and so forth. However, the sensitivity of their response proves in many applications to be insufficient. For instance, glow plugs in internal combustion engines having auto-ignition are designed, for rapid warmup purposes, for such high temperatures that their theoretical terminal temperature can be above the melting point of the glow pin jacket material. Then if problems occur during vehicle operation, such as excess voltage, short-circuit of a resistor, failure of one or more of the parallel-switched glow plugs, control unit failure, or sticking contacts, then pieces of the glow wire or glow pin can become detached. If they then reach the combustion chamber, which is quite possible in a spin-chamber engine, then engine damage can easily occur. For this reason, safety devices for electric consumers of this kind in internal combustion engines are considered to be of great importance. The conventional safety devices discussed above do not meet these stringent requirements.